Trevor Dummer

Measuring food availability and accessibility among adolescents: Moving beyond the neighbourhood boundary

Geographic methods have provided insight about food location availability and accessibility in understanding neighbourhood variations in health. However, quantifying exposure to food locations within a pre-defined range of an individuals residence ignores locations outside of the residential neighbourhood encountered in daily life. Global positioning system (GPS) data enables exploration of multiple contextual influences on health. This study defines place in relation to behaviour, employing GPS data to 1) describe adolescent food environments within and outside of the residential buffer, 2) quantify actual food location visits, and 3) explore associations between availability and accessibility of food locations and dietary intake. Adolescents (Nxa0=xa0380; ages 12-16), wore GPS loggers for up to seven days. Availability and accessibility of food locations were defined by counts and distances to food locations within a 15-min walk (1xa0km) of home, as well as within 50xa0m of an adolescents GPS track. We compared the proportion of food locations within the residential buffer to the proportion outside but within the GPS buffer. These proportions were compared to counts and distances to food locations actually visited. We explored associations between food location availability and accessibility with dietary intake variables. Food location availability and accessibility was greater and visits occurred more commonly outside of the residential buffer than within it. Food location availability and accessibility was greater for urban than suburban and rural adolescents. There were no associations between home-based measures of availability and accessibility and dietary intake and only one for GPS-based measures, with greater distance to convenience stores associated with greater fruit and vegetable consumption. This study provides important descriptive information about adolescent exposure to food locations. Findings confirm that traditional home-based approaches overestimate the importance of the neighbourhood food environment, but provide only modest evidence of linkages between the food environment beyond the residential neighbourhood boundary and dietary intake.

Cancer risk: Prevention is crucial

![Figure][1] nnILLUSTRATION: G. GRULLON/ SCIENCE nnAs cancer prevention scientists, we read C. Tomasetti and B. Vogelsteins Report “Variation in cancer risk among tissues can be explained by the number of stem cell divisions” (2 January, p. [78][2]) with considerable interest. Many of the

Premature mortality due to social and material deprivation in Nova Scotia, Canada.

IntroductionInequalities in health attributable to inequalities in society have long been recognized. Typically, those most privileged experience better health, regardless of universal access to health care. Associations between social and material deprivation and mortality from all causes of death´ a measure of population health, have been described for some regions of Canada. This study further examines the link between deprivation and health, focusing on major causes of mortality for both rural and urban populations. In addition, it quantifies the burden of premature mortality attributable to social and material deprivation in a Canadian setting where health care is accessible to all.MethodsThe study included 35,266 premature deaths (1995-2005), grouped into five causes and aggregated over census dissemination areas. Two indices of deprivation (social and material) were derived from six socioeconomic census variables. Premature mortality was modeled as a function of these deprivation indices using Poisson regression.ResultsPremature mortality increased significantly with increasing levels of social and material deprivation. The impact of material deprivation on premature mortality was similar in urban and rural populations, whereas the impact of social deprivation was generally greater in rural populations. There were a doubling in premature mortality for those experiencing a combination of the most extreme levels of material and social deprivation.ConclusionsSocioeconomic deprivation is an important determinant of health equity and affects every segment of the population. Deprivation accounted for 40% of premature deaths. The 4.3% of the study population living in extreme levels of socioeconomic deprivation experienced a twofold increased risk of dying prematurely. Nationally, this inequitable risk could translate into a significant public health burden.

Estimating the risk of bladder and kidney cancer from exposure to low-levels of arsenic in drinking water, Nova Scotia, Canada

Arsenic in drinking water impacts health. Highest levels of arsenic have been historically observed in Taiwan and Bangladesh but the contaminant has been affecting the health of people globally. Strong associations have been confirmed between exposure to high-levels of arsenic in drinking water and a wide range of diseases, including cancer. However, at lower levels of exposure, especially near the current World Health Organization regulatory limit (10μg/L), this association is inconsistent as the effects are mostly extrapolated from high exposure studies. This ecological study used Bayesian inference to model the relative risk of bladder and kidney cancer at these lower concentrations-0-2μg/L; 2-5μg/L and; ≥5μg/L of arsenic-in 864 bladder and 525 kidney cancers diagnosed in the study area, Nova Scotia, Canada between 1998 and 2010. The model included proxy measures of lifestyle (e.g. smoking) and accounted for spatial dependencies. Overall, bladder cancer risk was 16% (2-5μg/L) and 18% (≥5μg/L) greater than that of the referent group (<2μg/L), with posterior probabilities of 88% and 93% for these risks being above 1. Effect sizes for kidney cancer were 5% (2-5μg/L) and 14% (≥5μg/L) above that of the referent group (<2μg/L), with probabilities of 61% and 84%. High-risk areas were common in southwestern areas, where higher arsenic-levels are associated with the local geology. The study suggests an increased bladder cancer, and potentially kidney cancer, risk from exposure to drinking water arsenic-levels within the current the World Health Organization maximum acceptable concentration.

Small-area spatio-temporal analyses of bladder and kidney cancer risk in Nova Scotia, Canada

BackgroundBladder and kidney cancers are the ninth and twelfth most common type of cancer worldwide, respectively. Internationally, rates vary ten-fold, with several countries showing rising incidence. This study describes the spatial and spatio-temporal variations in the incidence risk of these diseases for Nova Scotia, a province located in Atlantic Canada, where rates for bladder and kidney cancer exceed those of the national average by about 25xa0% and 35xa0%, respectively.MethodsCancer incidence in the 311 Communities of Nova-Scotia was analyzed with a spatial autoregressive model for the case counts of bladder and kidney cancers (3,232 and 2,143 total cases, respectively), accounting for each Communitys population and including variables known to influence risk. A spatially-continuous analysis, using a geostatistical Local Expectation-Maximization smoothing algorithm, modeled finer-scale spatial variation in risk for south-western Nova Scotia (1,810 bladder and 957 kidney cases) and Cape Breton (1,101 bladder, 703 kidney).ResultsEvidence of spatial variations in the risk of bladder and kidney cancer was demonstrated using both aggregated Community-level mapping and continuous-grid based localized mapping; and these were generally stable over time. The Community-level analysis suggested that much of this heterogeneity was not accounted for by known explanatory variables. There appears to be a north-east to south-west increasing gradient with a number of south-western Communities have risk of bladder or kidney cancer more than 10xa0% above the provincial average. Kidney cancer risk was also elevated in various northeastern communities. Over a 12xa0year period this exceedance translated in an excess of 200 cases. Patterns of variations in risk obtained from the spatially continuous smoothing analysis generally mirrored those from the Community-level autoregressive model, although these more localized risk estimates resulted in a larger spatial extent for which risk is likely to be elevated.ConclusionsModelling the spatio-temporal distribution of disease risk enabled the quantification of risk relative to expected background levels and the identification of high risk areas. It also permitted the determination of the relative stability of the observed patterns over time and in this study, pointed to excess risk potentially driven by exposure to risk factors that act in a sustained manner over time.

Fruit and vegetable intake and body adiposity among populations in Eastern Canada: the Atlantic Partnership for Tomorrow’s Health Study

Objectives The prevalence of obesity among populations in the Atlantic provinces is the highest in Canada. Some studies suggest that adequate fruit and vegetable consumption may help body weight management. We assessed the associations between fruit and vegetable intake with body adiposity among individuals who participated in the baseline survey of the Atlantic Partnership for Tomorrow’s Health (Atlantic PATH) cohort study. Methods We carried out a cross-sectional analysis among 26u2009340 individuals (7979 men and 18u2009361 women) aged 35–69 years who were recruited in the baseline survey of the Atlantic PATH study. Data on fruit and vegetable intake, sociodemographic and behavioural factors, chronic disease, anthropometric measurements and body composition were included in the analysis. Results In the multivariable regression analyses, 1 SD increment of total fruit and vegetable intake was inversely associated with body mass index (−0.12u2009kg/m2; 95%u2009CI −0.19 to –0.05), waist circumference (−0.40u2009cm; 95%u2009CI −0.58 to –0.23), percentage fat mass (−0.30%; 95%u2009CI −0.44 to –0.17) and fat mass index (−0.14u2009kg/m2; 95%u2009CI −0.19 to –0.08). Fruit intake, but not vegetable intake, was consistently inversely associated with anthropometric indices, fat mass, obesity and abdominal obesity. Conclusions Fruit and vegetable consumption was inversely associated with body adiposity among the participant population in Atlantic Canada. This association was primarily attributable to fruit intake. Longitudinal studies and randomised trials are warranted to confirm these observations and investigate the underlying mechanisms.

RE: “ASSOCIATIONS OF BODY MASS INDEX, SMOKING, AND ALCOHOL CONSUMPTION WITH PROSTATE CANCER MORTALITY IN THE ASIA COHORT CONSORTIUM”

Fowke et al. (1) recently reported null associations between several risk factors for prostate cancer (bodymass index (BMI; weight (kg)/height (m)), smoking, and alcohol consumption) and prostate cancer mortality across 6 countries in southern and eastern Asia. The authors concluded that the lack of association they found casts doubt on the validity of these risk factors and that differences in prostate cancer mortality between Asian and Western populations may reflect variation in prostate cancer screening practices. The accompanying commentary (2) focused on the impact of screening on risk factors for cancer and suggested that understanding the etiology of cancers may be best accomplished through the study of populations without widespread screening. We agree with both sets of authors about the importance of assessing the impact of screening on cancer outcomes. However, concluding that the previously identified risk factors have limited utility is premature in the absence of highquality data on these risk factors and exposures. We suggest that inadequate assessment of potential risk factors is an alternative explanation for the observed null associations between BMI, smoking, and alcohol consumption and prostate cancer in southern and eastern Asia. One significant limitation of the study by Fowke et al. is that data on risk factors in the Asia Cohort Consortium were collected only at baseline, whereas cancer surveillance occurred over decades in some of the cohorts. Regarding tobacco, smoking status was limited to never smoking versus ever smoking at baseline. These available data could not identify how prostate cancer risk may have changed with changes in smoking behavior such as cessation. It is well-known that the risk of developing lung and other types of cancer decreaseswith smoking cessation and continues to decrease with more tobacco-free years (3). The BMI analysis presents an additional challenge. Although current World Health Organization BMI cutoff points are used for international classification of underweight, overweight, and obesity, there is considerable debate over interpretation of BMI cutoffs in Asian populations (4), with many authors suggesting that determination of overweight and obesity should be made at lower BMI levels in Asian populations (5, 6). Thus, the “healthy” reference BMI range of 22.5–24.9 in this study may have included persons with BMI-associated health risks and may have obscured associations between overweight/obesity and prostate cancer. Furthermore, as Fowke et al. mentioned in the Discussion section of their paper (1), the most consistent relationships between alcohol consumption and prostate cancer have been shown at higher levels of consumption than were present in the Asia Cohort Consortium (5). Thus, their analysis did not provide a basis for drawing conclusions about this potential risk factor. Lastly, it is important to consider the endpoint when assessing the impact of risk factors. For diseases with long latency periods and high survival rates such as prostate cancer, incidence rather than mortality may be a more appropriate endpoint for identifying etiological indicators (6). Prostate cancer mortality reflects the severity of the cancer, therapies received, and additional factors that may be independent of those that are linked with disease incidence. In summary, given the limitations of their data set, it is not surprising Fowke et al. found null associations (1). We suggest that this study demonstrates the need for better measurement of potential etiological variables to advance our understanding of the roles of both modifiable lifestyle risk factors and screening in the prevention and early detection of prostate cancer.

Multimorbidity in Atlantic Canada and association with low levels of physical activity

Owing to an aging population and medical advances, the anticipated growth and prevalence of multimorbidity has been recognized as a significant challenge and priority in health care settings. Although physical activity has been shown to play a vital role in the primary and secondary prevention of chronic disease, much less is known about the relationship between physical activity and multimorbidity. The objective of the present study was to examine the relationship between physical activity levels and multimorbidity in male and female adults after adjusting for key demographic, geographical, and lifestyle factors. The study drew data from a prospective cohort in Atlantic Canada (2009-2015). The sample included 18,709 participants between the ages of 35-69. Eighteen chronic diseases were identified. Physical activity levels were estimated based on the long form of the International Physical Activity Questionnaire. Using logistic regression analysis, we found that multimorbid individuals were significantly more likely to be physically inactive (OR=1.26; 95% CI 1.10, 1.44) after adjusting for key sociodemographic and lifestyle characteristics. Additional stratified analyses suggest that the magnitude of the effect between multimorbidity and physical activity was stronger for men (OR=1.41; 95% CI 1.12, 1.79) than women (OR=1.18; CI 1.00, 1.39) and those living in rural (OR=1.43; CI 1.10, 1.85) versus urban (OR=1.20; CI 1.02, 141) areas. Given the generally low levels of physical activity across populations and a growing prevalence of multimorbidity, there is a need for a prospective study to explore causal associations between physical activity, multimorbidity, and health outcomes.

1288 The effect of shift work on cardiometabolic health: findings from the atlantic path cohort study

Introduction Contemporary work environments increasingly rely upon a 24u2009hour work cycle resulting in more employees exposed to shift work. 30% of working age Canadians work evening, night and rotating shifts, and 21% of workers in the European Union. Compared to regular daytime work, shift work has the potential for disturbing sleep patterns and disrupting circadian rhythms with adverse health effects. Methods Participation was limited to volunteers from the Atlantic Canadian Provinces (Nova Scotia, New Brunswick, Newfoundland and Labrador, and Prince Edward Island). 12u2009413 participants, including 4155 shift workers and 8258 non-shift workers (matched 1:2 by age, sex, and education) from the Atlantic Partnership for Tomorrow’s Health (PATH) study. Multiple general linear and logistic regression models were used to assess differences in body adiposity and self-reported cardiometabolic disease outcomes between shift workers and non-shift workers. Results There was a significant increased risk of obesity and diabetes among shift workers compared to their matched controls. Shift workers were 18% more likely to be obese (95%u2009CI: 9 to 29) and 8% more likely to have abdominal obesity (95%u2009CI: 0 to 17). Shift workers were 31% more likely to have diabetes than non-shift workers (95%u2009CI: 11 to 56). The strength of this association was further demonstrated by controlling for participants’ fat mass index (FMI), which resulted in a 28% increased risk of diabetes among shift workers (95%u2009CI: 2 to 60). Despite the increased likelihood of being physically active, regular night shift workers had higher levels of BMI, waist circumference, and fat mass compared with matched controls. Conclusion Despite higher levels of physical activity and lower levels of sedentary behaviour, shift workers were more likely to have increased rates of diabetes and obesity and are subsequently at increased the risk of developing other chronic disease. The effects of shift work on cardiometabolic status may be independent of simple obesity.

How should we act on the social determinants of health

[See related article at [www.cmaj.ca/lookup/doi/10.1503/cmaj.180272][2]][2]nnKEY POINTSnThe concept of the social determinants of health was born out of the recognition that, although disease is a biomedical outcome, socioeconomic inequities are important drivers of disease variation globally,